There has been and continues to be a need for a techniques to safely encapsulate and to store hazardous nuclear waste generated from either defense, utility, or medical uses that both shields the environment from gamma, neutron, and x-ray particles. It is generally agreed that exposure to even low-level radioactive emission is highly undesirable.
The use of medicinal grade radioactive solutions is undergoing great expansion. Furthermore, Military defense use of radioactive materials in submarines and other areas creates additional levels of toxic radioactive materials. Safety issues exist today in the uranium enrichment plants, which have been decommissioned leaving behind a plethora of contaminated soils, equipment, and wastes that have to be properly disposed of. Moreover, utilities continue to create significant amounts of nuclear waste from power generation plants.
To date, the waste disposal process has largely been associated with the casking of waste into concrete castings, which have been dosed with absorbing materials such as fly ash or others. However, the absorbing materials can leach into the environment, if the concrete is damaged or cracked. Concrete is a hard and brittle material, which has a high potential for cracking, even when shrinkage naturally occurs as moisture escapes from it during a curing process. Cracking permits the escape of gamma radiation and the potential for radiation leaks.
Concrete castings are being utilized as safe storage techniques for radioactive waste at the disposal facilities and are optimistically expected to perform for hundreds of years as the radioactive materials decay to safe levels. The excessive weight of concrete and its thicknesses create transportation issues and further places limits on the practical size of storage containers.
In addition, the use of flyash in concrete (referred to as flyash concrete) has been the staple of the radioactive material shielding/absorption systems to date, since concrete has limits on the amount of solids, which may be added without effecting the structural integrity of the cement. Concrete has a degree of porosity, which allows for any moisture to eventually escape or permeate its structure, and many types of radioactive wastes have high levels of acidity, which can quickly attack concrete.
Accordingly, there continues to be a strong need for techniques, compositions, and materials that offer improved and cost effective radiation shielding. The techniques and compositions should improve the safety of handling, storing, transporting, managing, and disposing of radioactive waste.